This project is based on two experiments by Glaser and Griffin (1962). First, these investigators found that an established habituation of heart rate level can be maintained following bilateral lesions in the prefrontal cortex of the rat. A preliminary study in this laboratory has obtained similar results for the skin potential response of the rat. These observations seem to be opposed to current interpretations of the inhibitory influence of the prefrontal cortex on behavior. Second, Glaser and Griffin found that heart rate level and responses do not habituate after prefrontal lesions. This observation is in conflict with a prominent theory of the habituation process, the dual-process theory. In this laboratory, however, evidence has been obtained which suggests that heart rate habituation in the prefrontal rat could be interfered with by increased skeletal muscle activity. The purpose of this project is to repeat these experiments of Glaser and Griffin, using both heart rate and skin potential activity, and with control procedures not used in their experiments.